Need Advice for new project I want to Start

Hey Everyone! I Have a background with web technologies including PHP, some ajax, mysql, javascript, etc. I'm inspired by this: Lights I want to make a game that is freeroaming like this website but just an actual game of endless colors and fun! I've never done much with programming pc applications let alone games and am wondering where would be the best place to start? I want to have a lot of particle effects and of course like I said I just need some basis for a 3d flyable world. My instincts tell me C# is best, but even at that I have no clue where exactly to start. Could anyone point me in the right direction for my project?

[The Project]

Not related to the title but I want to make a game that is a flying freeroam world. This game will have no score and no objectives. The objects on the map will come into view and exist for a short period of time. The actual function of what decorates the randomly generated landscape is also going to be as unpredictable as possible. Perhaps clicking on some things causes them to explode like fireworks while others make the terrain shift. The camera will follow a sort of customizeable 'dreamer' or something similar to how it is seen in the link provided above. It will be essentially just a game to play while you're thinking about other stuff.